U.S. patent number 4,007,568 [Application Number 05/556,969] was granted by the patent office on 1977-02-15 for foundation for modular buildings.
Invention is credited to Bernard D. Soble.
United States Patent |
4,007,568 |
Soble |
February 15, 1977 |
Foundation for modular buildings
Abstract
A foundation for securely retaining a factory built structure,
such as a mobile home, modular building, or the like, having an
underframe including a pair of steel beams, to a land site. The
foundation includes a concrete pad with a pair of recesses for
containing the axles attached to the underside of the building
frame. The pad has cylindrical concrete piers extending through its
surface at spaced intervals forming two lines spaced at the same
distance as the beams of the underframe. Central cylindrical
cavities are formed in each of the piers and are adapted to receive
cylinders which extend downwardly from the underside of the frame
beams. The undersides of the beams rest on the top surfaces of the
piers and downturned flanges attached to the frame beams surround
the sides of the piers and restrain the structure against lateral
movement.
Inventors: |
Soble; Bernard D. (Detroit,
MI) |
Family
ID: |
24223548 |
Appl.
No.: |
05/556,969 |
Filed: |
March 10, 1975 |
Current U.S.
Class: |
52/294; 52/298;
52/126.1 |
Current CPC
Class: |
E04B
1/34352 (20130101); E04B 1/0007 (20130101); E02D
27/00 (20130101); Y10S 52/11 (20130101) |
Current International
Class: |
E04B
1/00 (20060101); E02D 27/00 (20060101); E04B
1/343 (20060101); E02D 027/00 () |
Field of
Search: |
;52/294,299,DIG.11,23,298,143,126,122,259 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Faw, Jr.; Price C.
Assistant Examiner: Friedman; Carl D.
Attorney, Agent or Firm: Krass & Young
Claims
Having thus described my invention, I claim:
1. A foundation for retaining a modular building having an
underframe employing a pair of elongated steel beams, comprising: a
concrete pad having a horizontal surface with dimensions at least
equal to the dimensions of the underside of the building; concrete
piers formed through the pad and extending downwardly from the
lower surface of the pad, said piers being arranged in two rows
spaced from one another by the same distance as the steel beams of
the building; first cylindrical steel tubes supported centrally
through each pier, and with the upper end of each tube
substantially flush with the upper surface of the pad, the lower
end of each tube being disposed substantially below the lower
surface of the pad; a plurality of second steel tubes having outer
dimensions complementary to the inner dimensions of the first steel
tubes so that the second steel tubes may telescope within said
first steel tubes; and means for securing one end of each of the
second steel tubes to the underside of the steel beams so that the
second steel tubes telescope within the first steel tubes and allow
vertical motion of the modular building relative to the pad while
restraining horizontal movement.
2. The foundation of claim 1 including means adapted to be secured
to the second steel tubes and supported in abutting relationship to
the surface of the pad surrounding said piers to maintain the
modular building in an elevated relationship with respect to the
pad.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a foundation arrangement for securing a
factory built structure having an underframe including steel beams,
to a land site, and more particularly to such an arrangement which
includes a concrete pad having pier structures adapted to support
the beams.
2. Prior Art
Mobile homes and offices, recreational vehicles, and like factory
built modular structures, hereinafter termed "modular buildings"
generally employ underframes constructed about a pair of parallel
spaced steel beams extending the length of the unit. The building's
wheels are supported on axles which may be permanently or
temporarily affixed under these frame members. When the buildings
are to be permanently or semi-permanently located at a site they
are jacked up to raise them off the wheels and piles of concrete
blocks or the like are stacked under the frame members and the unit
is then lowered onto these stacks. Various forms of tie-down straps
may be secured in the surrounding soil or to an underlying concrete
pad and joined to the frame to secure the unit against dislodgement
from the frame supports under forces imposed by wind and the like.
The piles of blocks are often hidden from view by skirts extending
between the edges of the underside of the unit and the ground or
pad.
These foundation arrangements were developed when mobile homes were
seldom retained at a site for longer than a single season. Modern
mobile homes are typically only mobile for the short period of time
required to move them from a factory or sales lot to a permanent
building site. In these relatively permanent structures such
makeshift foundation arrangements are far from satisfactory. First,
they are usually not very secure and the mobile homes frequently
tip over in high winds. Second, in order that the axles may clear
the ground the units must be elevated so that the door sills are
high above the ground and stairs must be provided to these doors.
Finally, the arrangement is often unsightly with the space between
the pad and the building used for storage of miscellaneous
objects.
SUMMARY OF THE INVENTION
The present invention contemplates a foundation arrangement for
such buildings which allows the beams forming the central part of
the underframe to be securely retained to a concrete pad formed on
the home site which strongly resists forces which would tend to
overturn the unit. The unit is positioned with its underframe faced
immediately above the concrete pad eliminating the need for
extensive skirting or high step arrangements. The resulting
structure is more physically attractive than units formed according
to the prior art arrangements.
In accordance with the present invention structures are formed
between the concrete pads and the beams of the mobile home's
underframe to permanently secure the two together to resist upward
displacement of the house from the pad as well as to vertically
support the structure on the pad.
These fastening structures include a plurality of piers formed
through the concrete pads and extending substantially below the pad
below the freeze line. The piers may be formed of concrete or of
steel or composition tubes and are preferably arrayed in two lines
along the length of the pad spaced at the same distance as the
beams forming the central part of the underframe of the building
structure. The upper surfaces of the piers are preferably separated
from the adjacent surfaces of the pad by a vertical shoulder. This
vertical shoulder may be formed by either elevating or depressing
the upper surfaces of the piers with respect to the adjacent
surfaces of the pad or by forming a circular cavity between the
adjacent surfaces of the piers and the pads.
The piers may have central vertical cavities formed downwardly from
their flat top ends. Mating concrete or steel cylinders are affixed
to the undersides of the frame members and adapted to project into
the cavities in the piers. Downturned flanges affixed to the frame
members around the cylinders engage the sides of the piers adjacent
to their top.
An alternate form of fastener member for joining the steel beams to
the pier tops includes a pair of cylindrical sections threaded to
one another so that the length of the section may be adjusted. One
end is affixed to the beam and the other end rests on the top of
the pier.
The pads are preferably formed with voids or recesses adapted to
receive axle structures which may be attached to the mobile homes
or the like so that the underframes may lie in close spaced
relationship to the surface of the pad, eliminating the necessity
for extensive skirting or step arrangements. The pads may also be
formed with recesses to receive jacks that can be used to support
the mobile structures while their wheels are removed, and to lower
them into engagement with the piers and pads.
Other objectives, advantages and applications of the present
invention will be made apparent by the following detailed
description of several preferred embodiments of the invention. The
description makes reference to the accompanying drawings in
which:
FIG. 1 is an elevational view through a mobile building structure
supported on a foundation arrangement formed in accordance with a
first embodiment of the present invention;
FIG. 2 is an upward view through the underframe structure of the
mobile home taken along line 2--2 of FIG. 1;
FIG. 3 is a downward sectional view taken along line 3--3 of FIG. 1
and illustrating the upper surface of the pad;
FIG. 4 is a sectional elevational view taken along line 4--4 of
FIG. 1 showing the end view of the pier structure of FIG. 1;
FIG. 5 illustrates an alternative form of pier structure wherein
the upper surfaces of the piers are substantially level with the
adjacent surface of the pad;
FIG. 6 is a sectional view through still another form of pier
structure wherein the piers are formed of tubes having their lower
ends depressed with respect to the adjacent surface of the pad;
FIG. 7 is a sectional view through an alternate form of adjustable
length coupling mechanism; and
FIG. 8 is a sectional view through the jack receiving recesses of
the pad illustrating the manner in which the mobile home structure
is lowered onto the pad.
As has been noted, the foundation arrangement of the present
invention may be used with mobile homes and like modular buildings.
The invention is hereinafter described in connection with a mobile
home, but that mobile home is to be considered merely
representative of the broader class of modular buildings.
A mobile home, as illustrated in FIG. 1, with a portion of its side
broken away to illustrate the structure of the frame, employs a
pair of elongated steel beams or tubes 10 which are disposed
parallel to one another and extend the full length of the modular
building. These beams are illustrated in FIGS. 1, 2 and 4 as being
I-beams, but alternatively could have other cross-sectional
configurations, such as a channel, box or the like. The I-beams 10
are typically disposed with their flanges aligned horizontally and
their web extending vertically.
The frame of FIGS. 1, 2 and 4, the I-beams are connected to
regularly spaced laterally extending frame members 12 welded or
otherwise fastened across the top flanges of the I-beams 10. The
frame may have front and rear axle housings 14 and 16 connected to
the I-beams and extending below them, carrying wheel hubs 18 at
their outer ends. The wheels of the mobile structure may be removed
from the housing when the unit is affixed to a building site.
The foundation arrangement includes a flat rectangular concrete pad
20 having longitudinal and lateral dimensions which are at least
equal to and preferably exceed those of the modular building
structure. The pad may typically have a thickness of from 5 to 10
inches. The pad is preferably formed with a pair of spaced
semi-cylindrical recesses 22 extending laterally across the pad and
adapted to receive the axle structure 14 and 16 of the mobile home
so that these may lie below the pad surface and allow the
underframe member to be supported in close proximity to the pad
surface.
The pad is also preferably formed with a number of slotted recesses
24 extending inward laterally from the side edges of the pad 20.
Four of the recesses are illustrated in FIGS. 1 and 3, but larger
numbers of these recesses may be alternatively provided. These
recesses are adapted to support jacks for use in lowering a modular
building structure onto the supporting foundation in a manner which
will be subsequently described.
The pad is formed with a plurality of downwardly extending piers 26
arranged in two rows. In the preferred embodiment of the invention
the piers are formed of the same concrete material as the pad 20
and are formed integrally with the pad adjacent to their upper
ends. The piers extend substantially below the bottom surface of
the pad, preferably to below the frost line in the Northern
climates, and may typically have a depth of 42 inches. The number
of piers used will be dependent upon the length of the pad
structure and the largest load that may be imposed on the
structure, but typically the pads will be spaced on approximately
5-10 foot centers so that from 5 to 10 of the piers might be used
for a 60 foot long pad. The spacing between the two rows of piers
is the same as the spacing between the two longitudinal beams 10 of
the underframe.
The upper surfaces of the piers 26 extend above the top level of
the pad 20 forming raised cylindrical caps 28. These caps may
typically project from 4 to 6 inches above the top surfaces of the
pad.
In order to secure the underframe to the pads, cylindrical,
downwardly dished steel fastener members 30 are welded or otherwise
attached to the undersides of the lower flanges of the beams 10 at
spaced intervals which coincide with the spacing between the piers
26. The inner diameters of the fasteners 30 exceed the outer
diameters of the upper ends 28 of the piers so that the fasteners
may extend over the piers and effectively cap them. The flat
underside of the fastener lies in abutment to the upper surface of
the pier and the inner diameters of the downturned flanges extend
over the sides of the pier.
In this relationship the axle housings 14 lie in the recesses 22,
allowing the underframe to be supported above the surface of the
pad by a distance equal to the height of the pier tops 28.
The underframe of the modular structure is thus supported at a
number of spaced points so that its weight is relatively evenly
distributed and does not impose any particular forces on the
relatively thin pad 20. The downturned flanges of the fastener
members 30 support the modular building against lateral displacing
forces such as wind and the like. Pin members 32 may be extended
horizontally through holes formed in the fasteners 30 and
complementary holes formed in the pier tops 28. Alternatively, lag
bolts could be fastened into the concrete of the pier top through
holes formed in the fasteners 30.
FIG. 5 illustrates an alternative form of pier and fastener
arrangement. A pad 40 is formed with a plurality of circular
apertures 42 through which concrete piers 44 are separately formed.
The upper surfaces of the piers may be level with or slightly below
the adjacent surface of the pad 40 and a cylindrical vertically
extending slot separates the two. This slot may be formed by an
appropriate mold used to cast the pier 42.
The piers 44 each have a central cavity 46 which extends downwardly
from their upper ends. The cavity 46 may extend through the full
length of the pier or may terminate short of the bottom. A
cylindrical dished fastener 48 with downwardly directed flanges is
welded to the lower flange of the beam 10 and extends over the top
of the pier 44 with the flanges extending into the cylindrical slot
between the pier and the adjacent pad surface. The fastener 48 has
a cylindrical steel tube 50 welded to its underside and projecting
downwardly. This tube fits within the central cavity 46 formed in
the pier 44 and acts as an additional stabilizing element. Various
forms of horizontal pin arrangements may be used to secure the
fasteners 48 to the pier top. This arrangement allows even closer
spacing between the underframe and the pad surface since the bottom
surface of the flanges may lie directly in abutment to the pad
surface.
Another pier arrangement is illustrated in the drawing of FIG. 6.
The modular building is illustrated as having longitudinal frame
members consisting of box sections 60 secured to laterally
extending frame members 64.
The concrete pad 66 is formed with a plurality of depressed
cylindrical sections 68 and tubular piers 70 extend through
apertures 72 in the central section of each depressed area and
project substantially below the bottom of the pad structure. The
tube 70 may be formed of steel or alternatively a cast or molded
concrete or composition material.
The upper end of each of the tubes 70 is formed with a horizontal
flange 74 which lies in abutment to the bottom of the cylindrical
depression 68. Nut and bolt fasteners 76 pass through holes formed
in the flange 74 and through mating holes in the bottom surface of
the pad beneath the recess 68 to secure the tubes in position.
The fastener for joining the underframe to the pad and pier
structure includes a disc-like plate 77 welded to the underside of
the box beam 60 and having a steel tube 78 welded to its underside
and projecting vertically below the disc. The outer diameter of the
tube 78 is complementary to the inner diameter of the pier tube 70
and the two are arranged coaxially. Appropriate gaskets 80 of a
resilient material may be formed between the underside of the
mobile structure and the adjacent upper surface of the pad 66 to
form a water-tight seal therebetween.
An alternate embodiment of fastener member is illustrated in FIG.
7. While this fastener is specifically designed for use with a pad
of the type illustrated in FIG. 1, having a raised pier surface
extending above the adjacent pad surface, similar fasteners could
be used with the pier embodiments of FIGS. 5 and 6.
The fastener of FIG. 7 is illustrated as attached to a box beam 90
forming one of the longitudinal beams of the modular building
underframe. A trunion fastener 92 straddles the box section 90 and
is connected thereto by a pin 94 which may be welded to the box or
simply inserted through holes in the box. A disc-shaped plate 96 is
welded to the underside of the trunion mount 92 and has a
downwardly extending internally threaded tubular member 98 formed
integrally therewith. An externally threaded tube member 100 is
affixed to the upper side of downwardly dished cap fastener 102 and
makes a threaded engagement with the tube 98. Thus the length of
the fastener between the upper surface 104 of a pier formed in a
pad 106 and the longitudinal beam 90, may be adjusted. A lock nut
108 may be used to secure the mating threaded sections 98 and 100
in their adjusted position.
FIG. 8 illustrates the manner in which jacks may be inserted in the
recesses 24 formed laterally inwardly from the sides of the pad 20
in order to lower a modular building structure 120 onto a suitable
pier surface. Trenches 122 may be formed in the supporting soil
surface beneath the recesses 24 and jack members 126 having
extensible rod members 128 may be slipped into the recesses 24 and
the trenches 122 on the laterally outer sides of the pads. The
jacks may be extended so as to support the modular building, while
its wheels are removed, and allow it to be slowly lowered so that
the appropriate fastener members attached to the underframe are
secured to the piers.
Alternatively, a conventional sling arrangement may be placed under
the mobile home and supported with jacks disposed outside of the
pad area to lower the building into place.
The foundation arrangement thus described is accordingly relatively
simple in form and securely retains modular buildings in a
permanent fashion.
* * * * *